An endoribonuclease based incoherent feedforward loop for decoupling resource limited genetic modules

A significant goal of synthetic biology is to develop genetic devices for accurate and robust control of gene expression. Lack of modularity, wherein a device output does not depend uniquely on its intended inputs but also on its context, leads to poorly predictable device behavior. One contributor to lack of modularity is competition for shared limited gene expression resources, which can induce 9coupling9 between otherwise independently-regulated genes. Here we quantify the effects of resource competition on engineered genetic systems in mammalian cells and develop a feedfoward controller to make gene expression robust to changes in resource availability. In addition to mitigating resource competition, our feedforward controller also enables adaptation to multiple log-orders of DNA copy number variation and is predictably tunable with upstream open reading frames. Our resource competition characterization along with the feedforward control device will be critical for achieving robust and accurate controlof gene expression